Oil compositions containing metal salts of ricinoleate dithiophosphoric acids



mumm- United States Patent 011. coMPosrrroNs CONTAINING METAL SALTS orRICINOLEATE nrrmornosrnonrc ACIDS James M. Boyle, Bayonne, and CharlesS. Lynch, Plainfield, NJ., and Harold R. Ready, Decatur, ]ll., assign--ors to Esso Research and Engineering Company, a

corporation of Delaware I 3 No Drawing. Original application Feb. 9,1955, Ser. No.

487,212, now Patent No. 2,895,973, dated July 21, 1959. Divided and thisapplication Apr. 17, 1959, Ser.No. 807,026 r 8 Claims. 01. 252-325 Thisinvention relates to a new class of chemical compounds, to methods ofpreparing such compounds and to lubricating oil compositions containingsuch compounds as useful additives. More particularly, the inventionrelates to metal salts of ricinoleate dithiophosphoric acids.

This application is a division of Serial No. 487,212, filed February 9,1955, now US. Patent No. 2,895,973.

The utilization of additives in lubricating oil composi- I tions is wellknown These additives are used to improve one or more characteristics ofthe lubricating oil compositions such as viscosity index, pour point,wear resistance, H

oxidation resistance, corrosion resistance, extreme pressure resistancedetcrgency, and the like, and are employed extensively in lubricatingoil compositions for internal.

combustion engines such as automotive and aviation engines. tion, thereis a continuing and critical need for new and improved additives whichare capable ofimparting improved characteristics to the lubricating oilcompositions. Preferably, such new additives will improve more than onecharacteristic or property of the oili A new class of compounds has nowbeen found which are exceedingly useful as additives for lubricating oilcompositions. These new compounds of this invention are effectivemulti-purpose lubricating oil additives imparting properties ofdetergency, wear resistance and extreme pressure resistance to thelubricating oil compositions containing them. Such compositions areparticularly useful for lubricating internal combustion engines. Thecompounds of this invention have the general formula of the resultantester, which is attributable to the aliphatic monohydroxy monocarboxylicacid is reacted with phosphorusfpentasulfide with the evolution ofhydrogen sulfide. The resultant bis-ester dithiophosphoricacid isneutraliz'e'd with a basic reacting compoundiof an alkaline earth metalto form the dithiophosphates ofthis invention.

The aliphatic monohydroxy monocarboxylic acids usethis invention arericinoleic acid and condensation,

Due to the increasing severity of engine opera-' 2,947,693 Patented Aug.2, 1960 polymers thereof. Ricinoleic acid has the general formulaCondensation polymers of ricinoleic acid may also be employed in formingthe esters of this invention. These condensation polymers are formed byreacting the carboxylic group of one molecule with the hydroxyl group ofanother molecule with the elimination of water by a self-esterificationreaction. Thus, from 2 up to 6 or more molecules, preferably about -2 to4 molecules, of ricinoleic acid may be combined to form a condensationpolymer containing one free carboxylic acid group and one free hydroxylgroup. Thus, for example, di-, tri-, tetra-,

penta-, and hexa-ricinoleic acid may be formed. The

condensation reaction may be carried out simply by heating ricinoleicacid at a temperature above about 210 F. as is well known in the art.This reaction generally forms a mixture of polyricinoleic acids. Suchmixtures may be employed in this invention. These conden- I sationpolymers may then be esterified to form esters useful in this invention.

The aliphatic monohydric alcohols useful in this invention generallycontain in the range of about 1 to 20 carbonatoms. The number of carbonatoms in the alcohol .is not too critical and generally the use ofrelatively inexpensive alcohols is preferred. Particularly desirablealcohols have the formula ROH where R is an alkyl radicalcontaining inthe range of about 1 to 20 carbon atoms. Specific examples of thealcohols which may be employed in the present invention include methyl,ethyl, propyl, isopropyl, butyl, amyl, octyl, 'decyl, dodecyl, andoctadecyl. OX0 alcohols prepared by the well-known OxoF process such asO; Oxo alcohol, C Oxo alcohol, C Oxo alcohol and C Oxo alcohol may alsobe employed if desired.

The dithiophosphates of this invention are prepared in the followingmanner. An aliphatic monohydric alcohol (or a mixture of differentaliphatic monohydric alcohols) of this invention is esterified with analiphatic monohydroxy monocarboxylic acid (or mixtures of differentaliphatic monohydroxy monocarboxylic acids) of this invention.Generally, about 1 mole of the aliphatic monohydric alcohol will beemployed per mole of monohydroxy monocarboxylic acid. Thisesterification is carried outcmploying conventional esterificationconditions well known to the art. A water'entrainer such as benzene andan esterification catalyst such as sodium acid sulfate may be employedif desired and esterification temperatures in the range of about 180 F.to 300 F.

, are preferred. The completion of the esterification reaction will beindicated by the cessation of water forma-tion which generally occursafter about 2 to 5 hours.

Then about 4 moles of the ester (or ester mixture) formed as describedabove is reacted with about 1 mole of phosphorus pentasulfide (P 8 Thisreaction is preferably carried out at a temperature in the range ofabout 150 to 250 F. until evolution of hydrogen sulfide therefromessentially ceases, which generally occurs after about 1 to 5 hours. Anyunreacted phosphorus pentasulfide may be filtered from the remainder ofthe reaction mixture.

The resultant dithiophosphoric acid isthen neutralized with a basicreacting compound of an alkaline earth metal or zinc. Generally about 2moles of the dithiophosphoric acid will be employed per mole of thebasic reacting compound of the metal. If desired, mixtures of diiferentbasic reacting compounds of different metals may be employed. Examplesof basic reacting compounds which may becmployed include the oxides,hydroxides and car bonates of the metals: zinc, barium, calcium,strontium andrnagnesium. Zinc is the preferred metalin the pres: entinvention. Any water formed in the neutralization reaction may beazeotroped off from the reaction mixture with a water entrainer such asbenzene. The resultant aw.m..-

dithiophosphate may be blended into a solvent such. a

mineral lubricating oil to form an additive concentrate.

Particularly preferred compounds of the present invention have thegeneral formula where R and; R are alkyl radicals containing in therange of; about 1 to 20 carbon. atoms. A particularly preferred compoundof this type is one in which both R and R are methyl groups derived frommethyl alcohol.

In certain instances it may be desirable to use as lubricating oiladditives dithiophosphates prepared by re.- acting a mixture of aricinoleate ester and an aliphatic monohydric alcohol with P 8 andneutralizing the resultant dithiophosphoric acid with abasic-reactingcompound of an alkaline earth metal. Mixed dithiophosphates prepared asabove would have the general formula:

where R OOCR O- is the residue ofthe ricinoleate ester. and R O is theresidue of the aliphatic monohydric alcohol. The alcohol, R OH, fromwhich R' O-- is derived can contain in the range. of about 1 to 20carbon atoms. Preferably R is an alkyl radical containing 1 to 20 carbonatoms, preferably 3 to 8 carbon atoms. Examples of such alcohols (R QH)would be the same as disclosed heretofore for the alcohols useful inpreparing the ricinoleate esters.

The invention will be more fully understood by reference to thefollowing example. It is pointed out, however, that the example is givenfor the purpose of illustration only and is not to be construed aslimiting thescope of the present invention in any way.

EXAMPLE Preparation of zincbis-(methyl ricinoleate) dithiophosphate A,compound. of this invention, namely, zinc bis- (methyl ricinoleate)dithiophosphate, was prepared in the. following manner: A mixture of 4.3moles methyl ricinoleate and 1 mole of phosphorus pentasulfide washeated at ZOO-220 F. for 90 minutes. The small amount of.unreactedphosphorus pentasulfide was removed by filtra-= tion. An equalweight of mineral oil having a viscosity at. 100 F. of 100 S.U.S. wasadded to the product. This concentrate was then heated at ZOO-250 F.over 1 hour with 1.1 moles of zinc oxide- Benzene-was introducedtoazeotrope the residual water. Filtration of: the excess basegaveapaleyellQW concentrate having the following properties:

Viscosity 210 F., S.U.:S. 52.3.

Viscosity index 130, Pr e t,- 1 Sulfur, p rc nt -7 Detergencypropertiespf additive A in lubricating oil compositions Additive A wasevaluated as a lubricating oil detergent in a phorone-H SO test inaccordance with the procedure set forth in Serial Nos-3275216, now US.2,732,285, by Elmer B. Cyphers and Charles S. Lynch. This particularlaboratory test has been found to give :anexcellent correlation with theperformances of-lubricating oil compositions in. diesel. engines,particularly with: respect a to' caterpillar ring qzone deposits. Thebase oil',::hereinafter; referred to. as base. oil :I, employed in thistest consisted of (1) vol. percent of a solvent refinedminerallubricating oil havingyan,S.U.S. ,viscosity at 210 F. oi. about 66seconds and a viscosity indexof 103 and-(2) 5. vol. percent of aconventionaldetergent-additive:hereinafter referred to as additive B.This. 1 conventional detergent additiVe,,additiV.e B, consisted of (1)about 62.5% by weight ofan oil'solution containing as the activeingredient 40% by weight of a P S -treated barium diisobutyl: phenolsulfide. and .(2) about, 37.5% ofi an: oil solution containingtheflactive ingredient. about. 30% a by weight of. a calciumlfal ylbenzene sulfonate. Bases. oil I and a blend of baseoil [I andadditive Awereeach. evaluated in thephoroneaI-IgSO test andth'e following;results-were. obtained:

TABLE.I;.--PHORONE.TEST RESULTS 1 Additive concentration. expressed: on;total COmPOSRIOXIQZL In the phorone' test the greater the amount of 10%1 H 804 which canbe added to-the lubricating oil -corn-= position, thebetter is the lubricating oilcomposition from a detergency standpoint.-It will'be-notedthat the'oil'i composition containing l wt; percent ofadditive'A-(or' 0.5% by weight of zinc di-(methyl' ricinoleate) dithiophosphate) showed a substantially superior performance in thephoronetest. More-specifically; 5.6 CCSxOf 10% H 80 couldbe addedto thebase oil containing additive A, whereas only 5.2 ccs.of10.%H SO could beadded to the base on alone.- The" difference of 4 0.'4"cc'. represents asubstantial diflerence in the phorone-test since when 5:6 ccs. of'10%'HS O are addedto" base oiI*I,' more than fifty-times more'vhardresinous decompositionproducts (phoronedeposits) are formedthan'when'utiliv ing only 5.2 cos. of H 80 It will also be noted that ahard type of deposit wasformedwhen utilizing base oil I, whereas when:using base oil I containing a small amount of additive A, a soft type ofdeposit was formed.

The extreme; pressure and anti-wear properties .ofii'zinc bis-(methylricinoleate) dithiophosph'ate were: measuredi by the Shell 4-ballE.P..'- testers. Results from. this test are" significant in that ztheyrcorrelate:-with. valve train wear: j data from :automotivefieldz tests.Briefly, the. Shell.;4-.. ball ELP. test is .carried; .out=;as:=follows:;, Three:-. /z-inch-; diameter-steel balls; are rigidly;clamped in a reservoiri containing the test. oils A measured. load isapplied; through a fourthball which rotates at; 1500 -r.p. m..-inr.-contact with-theotherfi. The-highest loadat whichthe 3 fixed balls,show..no;.noticeable. wear. after 10. seconds a measure of the. filmstrengthof the lubricant... The base oil, hereinafterreferred .to. asbase oil,.II,.emp1oye d:-in thisyi. test. consisted of1.).82:,.vol..percent..oa solvent refined, mineral lubricatingfloilhaying. an S.U.S. .viscosity at .1003. i Fgof about anda viscosityindex. of about. 105, 12 16.21vol. jpercent ofa, viscosity. indeximprover concentrates; containing as the active ingredient about 20% byweight TABLE IIr-SHELL -BALL El. TESTER RESULTS Composition Evaluated lSeizure Load, kg.

Base 011 II 60 Base Oil II 6 wt. percent of Additive A 90 Base 01111 6wt. percent of Additive B. I 70 Base 011 II 1 wt. percent of Additive A5 w Additive B- l- 85 Additive concentration based on total composition.

In the Shell 4-ball E.P. test, the higher the seizure load the better isthe lubricating oil composition from an antiwear standpoint. It will benoted that the addition of 6 wt. percent of additive B to base oil 11gave only a slight improvement in this test. On the other hand, theaddition of 6 wt. percent of additive A (3 wt. percent of zincdi-(methyl riconoleate) dithiophosphate) tobase oil II increased theseizure load in the test by 30 points. Lubricating oil compositionsgiving seizure loads above 80 are'outstanding in this test. It will alsobe noted that the. addition of 1% by weight of additive A and 5% byweight of additive B to base oil II produceda seizure load of 85 whereasthe result attributable to this particular combination of additive A andadditive B based upon the additive effects of these two additives wouldpredict a seizure load of less than 80.

Generally speaking, the lubricating oil compositions of this inventioncomprise a major proportion of a lubricating oil and a small amount ofthe novel compound (or mixtures of compounds) of this invention.Preferred concentrations of the dithiophosphates of this invention arein the range of about 0.01 to by weight and even more preferably in therange of about 0.1 to 5% by. weight, based on the total lubricating oilcomposition. In certain instances, a greater or lesser proportion may beemployed if desired. In general, it is preferred to market thedithiophosphates of the present invention as additive concentratescontaining about 10 to 75 wt. percent of the dithiophosphate, based onthe additive concentrate. The remainder of the additive concentrate isgenerally a diluent oil, preferably a mineral lubricating oil.

The lubricating oil base stocks used in the compositions of thisinvention may be straight mineral lubricating oils or distillatesderived from paraffinic, naphthenic, asphaltic or mixed base crudes, orif desired, various blended oils may beemploycd as well as residuals,particularly those from which asphaltic constituents have been carefullyremoved. The oils may be refined by conventional methods using acid,alkali and/ or clay or other agents such as aluminum chloride, or theymay be extracted oils produced, for example, by solvent extraction withsolvents of the type of phenol, sulfur dioxide, furfural, dichloroethylether, nitrobenzene, crotonaldehyde, etc. Hydrogenated oils or whiteoils may be employed as well as synthetic oils prepared, for example, bythe polymerization of olefins or bythe reaction of oxides of carbon withhydrogen or by the hydrogenation of coal or its products. In certaininstances cracking coal tar fractions and coal tar or shale oildistillates may also be used. Also for special applications variousorganic esters or animal, vegetable or fish oils or their hydrogenated,polymerized or voltolized products may be employed, either alone or inadmixture with mineral oils.

Synthetic lubricating oils having a viscosity of at least 30 S.S.U. at100 F. may also be employed such as esters of monobasic acids (e.g.ester of C Oxo alcohol with Cg Oxo acid, ester of C Oxoalcohol withoctanoic acid, etc.), esters of dibasic acids (e.g. di-2-ethyl hexylsebacate, di-nonyl adipate, etc.), esters of glycols (e.g. C Oxo aciddiester of tetraethylene glycol, etc.), complex esters (e.g. the complexester formed by reacting one mole of sebacic acid with two molesoftetraethylene glycol and two moles of 2-ethyl-hexanoic'acid, complexester formed by reacting one mole of tetraethylene glycol with two molesof sebacicacid and two moles of 2-ethyl hexanol, complex ester formed byreacting .together one mole of azelaicj acid, one mole of tetraethyleneglycol one mole of C Oxo alcohol, and one mole of C Oxo acid), esters ofphosphoric acid (e.g. the ester formed by contacting three moles of themono methyl ether of ethylene glycol with one mole of phosphorusoxychloride, etc.), halocarbon oils (e.g. the polymer ofchlorotrifluoroethylene containing twelve recurring units ofchlorotrifluoroethylene) alkyl silicates (e.g.. methyl. polysiloxanes,ethylpolysiloxanes, methyl-phenyl polysiloxanes, ethylphenylpolysiloxanes, etc.), sulfite esters (e.g. ester formed by reacting onemole of sulfur oxychloride withtwo moles of the methyl ether of ethyleneglycol, etc.), carbonates (e.g. the carbonate formed by reacting C Oxoalcohol with ethyl carbonate to form a half ester and reacting this halfester with tetraethylene glycol), mercaptans (e.g. the mercaptal formedby reacting Z-ethyl hexyl mercaptan With formaldehyde), formals (e.g.the formal formed by reacting C Oxo alcohol with formaldehyde)polyglycol type synthetic oils (e.g. the compoundv formed by condensingbutyl alcohol with fourteen units of propylene oxide, etc.), or mixturesof any of the above in any proportions. Also mixtures of mineral oilsand the aforementioned synthetic oils may be utilized if desired. i Forthe best results the base stock chosen should normally be that oil whichwithout the new addition agents present gives the optimum performance inthe service contemplated. However, since one advantage of a the agentsis that their use also makes feasible the employment of lesssatisfactory mineral oils or other oils, no strict rule can be laid downfor the choice of the base stock. Certain essentials must of course beobserved. The oil must possess the viscosity and volatilitycharacteristics known to be required for the service contemplated. Theoil must be a satisfactory solvent for the addition agent, although insome cases auxiliary solvent agents may be used. The lubricating oils,however they may have been produced, may vary considerably in vis cosityand other properties depending upon the particular use for which theyare desired, but they usually range from about 40 to 150 seconds Sayboltviscosityat 210 F. For the lubrication of certain low and medium speeddiesel engines the general practice has often been to use a lubricatingoil base stock prepared from naphthenic or aromatic crudes and having aSaybolt viscosity at 210 F. of 45 toseconds and a viscosity index of 0to 50. However, in certain types of diesel service, particularly withhigh speed diesel engines, and in aviation engine and other gasolineengine service, oils of higher viscosity index are often preferred, forexample, up to 75 to 100, or even higher viscosity index.

, In addition to the compounds to be added according to the presentinvention, other agents-may also be used. One of the more importantadditive materials to beused with the base stock of the presentinvention is a viscosity index improver. The finished lubricating oilfor automotive use should have a high viscosity index. A preferredviscosity index improver' as well as thickening agent is a highmolecular weight polymerized olefin, such as polymerized C to C olefins.For example polymerized butenes and preferably polymerized isobutenehaving a molecular weight in the range of about 5,000 to 50,000,preferably about 10,000 to 25,000, and even more preferably about 15,000to 20,000, are useful.

Theseadditives' are especially suitable for'increasing-the viscosityf"the light neutral oilseand other light dis- SlUfSPa-t 210 1 bythe useofthese VJ. thickening agent's; In'ordcr toincrease viscosity and toimprove viscosity index of thefinished lubricant by as-much as l0 tov70-units, it is generally desired to employ in the rangeofalioutfll to10.0 wt. percent; preferably -1 to 55%; andeven. more preferably about 2to 4%, of the polyolefin b'ased'on the finished lubricating oil. Otherviscosity index'improvers include the polymethacrylate esters,fu'rnarate-vinyl acetate copolymers, polyalkylstyrenes; andxth'e like;Finished lubricants. containing a mixtu're ofpolyolefins andpolyesters'may be formulated.v

'Ihusfrom'fl to-I0% of polybuteneand l to 3% of a polyester may be used.

ln addition to'the dithioph'osphates of this invention which act asdetergent additives, it will be understood that-other detergentadditives may be employed inlcombination. therewith.

sulfides, phosphosulfurized metal alkyl phenol sulfides, metal=sulfonates andmixtures thereof. Specific exam-- ples: of. metalalkyl"phenol. sulfides which may be employed. include barium tert. octylphenol sulfide, calcium tert. octyl*phenol:sulfide, calcium-barium tert.octyl phenol.sulfide,calci1im nonyl' phenol sulfide; barium nonylphenol: sulfide, calcium-barium amyl phenol sulfide andthezlike;Alkaline earth metal alkyl phenol sulfides are.particularlyrpreferred.Preferably themetal al-kyl phenol sulfides contain one zalkyl groupcontaining in the.

range of about 4 to 24 carbon atoms attached toeach benzene nuclei. Thereactionproducts of phosphorus pentasulfide withtanyof thev above-'metalalkyl phenol sulfides are-also. especiallypreferred detergent additives:useful inlubricating 'oil compositions of the present.

furizedhydrocarbons, for example P S -treatedp olyisobutylener,Generally these-detergent additives (other than the dithiophosphatesoftheipresent invention) willbeo-used:in;-concentrations of about 0.1to%,' preferr ablyrabout=0.-5 t o*5% by;-weight; based on thetotalcomposition; 1

'In-1,additionto .--the=.;materials mentioned above, thelubricatingoilcompositions may also include other addi fives-such asdyes; pour sdepressors; anti-oxidants, solvents, assisting*agentsand-the: like. .Specific examples of,

such. other compounds? include chlordibenzyl" disulfide;sulfurized-spermoil," voltolized. sperm 1 oil; phenylalphanaphthylamine, diamyl trisulfide, sulfurized wax olefins',

tricresyl=phosphate; and 2,6-di-tert. buty1-4-methyl phenol.

Solv'entsand. assisting agents, such as esters, ketones, alcohols,thioalcohols,-amines, aldehydes, halogenated or nitratedcompounds,andthe like,may also be employed.

In. additionto being: employed as lubricants, the additivesoflthepresentinvention may also beused in. other Particularly preferreddetergents" which maybe employed: in combination with the dithiophosphates? of this" invention include metal 'alkyl phenol:

mineral oil-products =suoh as-motor fuels; hydraulic fiuidsn:torque-converter fluids, cutting:oils; flushingaoils, :trans formeroils," industrial oils, process oils; and thexlike and: generally'asuseful additives in ol'eaginoussproductsi LTheyi may *aIso b'e used: ingear lubricants; .greasesr and? othen': products containing: lubricatingfoils' as :ingredientsx.

l. A lubricating oil composition comprisingz a imaiorz proportion -:of.lubricating oiL' and about .0.01:to 10% by weightof-a compound.ofatheiormula.

where R and; R5 are alkyl -radicals 5 containing =1 to :20? carbonatoms,- -OCR O and--OCR O- dues ofaliphatiemonohydroxy"-monocarboxylio-acids selected "from the group iconsisting of ricinoleicxacid and condensation polymersthereof having inthe rangeof 2 to- 6 ricinoleic' groups per molecule; andMis. ametalselected from the group consisting. of 'alkaline earth metals andzinc.

2; A lubricating, oil composition according to claim 1"Wherein'saidioilis a mineral' lubricating oil;

3. A lubricating oil composition according. to claiifil" wherein saidacidis' ricinoleic acidi I 4'. A lubricating oil "compositionaccording'tolclaim 1" wherein said metalis zinc;

5". A mineral lubricating oil "composition comprising a majoramount'of'mineral lub'ricating'oil and about 01 1" to 10.0% by'wei-ghtrbasedon the weight"ofs'aidfltotail'oom= position of'a compound of theformula where R and; R "are alkyl radicals: containing-in the! range ofaboutl to 20 carbon atoms.

6.: A lubricating oil composition according to claim 5* wherein R and R'are both mcthylgroups: I

7. An. additive concentrate consistingxessentially: of 1040 by weight ofzinc bis-(methylricinoleate)?div thiophosphate and a mineral oil. I

8. An additive concentrate consisting essentiallyof. mineraloil andlO to75%.by weight of acompound o the formula where 'R fand' R are alkylradicals containing 1 to ZO? carbon atoms;v --OCR O-- and -i-OCR O areresidues of aliphatic monohydroxy: monocarboxylic' acids selected fromthe group; consisting of .ricinoelic acid and .lconden sationpolymeisthereof having" in the rangexof Z to's6: ricinoleic groups. permolecule, and M'isa metal-selected. from the group-consisting; ofalkaline earth metals and zinc.

No references cited.

1. A LUBRICATING OIL COMPOSITION COMPRISING A MAJOR PROPORTION OFLUBRICATING OIL AND ABOUT 0.01 TO 10% BY WEIGHT OF A COMPOUND OF THEFORMULA